Smart cards are widely used for a variety of applications, and in particular are used as bank cards, such as credit or debit cards, to authorize financial transactions for a user. Such cards are often colored over the entire smart card body aside from contacts, either for aesthetic appeal, to reflect branding of the card-issuing company, or a combination thereof.
To provide a physical card-reader contact for the smart card, a separate module is constructed and then inserted into the smart card body during assembly. Such smart card modules typically comprise a robust electrically conductive interface which can make physical contact with contacts within a card-reader, and an integrated circuit chip internal to the smart card which is electrically coupled to the conductive interface.
There are various methods of attaching an integrated circuit chip to the conductive interface, but all involve providing a substrate onto which the conductive interface can be mounted so as to face outwardly on the smart card, thereby providing sufficient structural support to be able to attach electrical connectors to the integrated circuit chip.
The substrate is generally chosen from one of two materials: epoxy glass, which is an FR4 material and is usually colored so as to be yellow, grey or black; or polyethylene terephthalate (PET) which is either transparent, or dyed black or white. Regardless of how the colored smart card module is installed into the smart card, at least a portion of the substrate will be visible to a user, and the coloration of the substrate can diminish the aesthetic appeal of the overall smart card.
To obtain a colored PET, the transparent material is dyed with either black or white dye. This dye impacts the adhesion of electrically conductive material to the surface of the substrate, making it difficult to provide an integrated circuit connection element on the substrate, substantially increasing the risk of connection failure. The application of this dye is also relatively expensive, increasing the cost-per-unit to manufacture a smart card module by a significant percentage. Different dye colors can be utilized, but, due to the small numbers typically required, are not due to the extensive testing required to make sure robustness is maintained over the life of the module.